You could set your system to a higher scale, keeping the 4k desktop. System, Display, Scale and Layout subheading, Scale, try 150%.
Or if you mean the in sim UI (HUD etc) you can edit the scale of fonts etc.
See this post in the FAQ subforum / section;
https://simhq.net/forum/ubbthreads....font-sizes-in-tac-and-labels#Post4328916WOFF defaults to desktop res, some systems report the resolutions differently compared to others, so it's a fallback method.